Zigzag sewing machines



Sept. 30, 1958 T. J. zYLBERT ZIGZAG SEWING MACHINES Filed Dec. 5, 1955 Hllllllllll'llll mmummn Il Fig.|

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INVENTOR. Thaddeus J Z y/berf BY w/r/vEss United States Patent O ZIGZAG SEWING MACHINES Thaddeus J. Zylbert, South Plainfield, N. J., assigner to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application December 5, 1955, Serial No. 550,948 4 Claims. (Cl. 112-158) 'This invention relates to sewing machines and more particularly to needle-jogging, zizgag sewing machines.

From a practical standpoint, it is impossible to manufacture all sewing machines with exactly the same tolerance between parts. The clearance between the moving parts of some machines as they come from the production line may be slightly less than average. These machines are said to be stili In other machines the clearance between moving parts may be slightly greater than average. These machines are termed loose In order that all needle-jogging zigzag sewing machines may be adjusted to function properly, when they leave the factory, it is desirable to provide each machine with a means for adjusting the spring bias applied to the swinging gate thereof. Therefore, the primary object of the present invention is to provide an improved device of this character.

Another object of the invention is to provide means for adjusting the spring bias applied to the swinging gate of a needle jogging sewing machine, which means for adl justing will be easily accessible for adjustment, but which will be hidden from view when the sewing machine is in operation.

With the above `and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention 4and the advantages attained thereby will be readily understood by those skilled in the art.

-In the drawings:

Fig. 1 is a side elevational sectional view showing the head portion of the bracket-arm of a sewing machine embodying the present invention; and

Fig. 2 is an end view of the bracket-arm taken along the line 2 2 of Fig. l.

The preferred embodiment of the invention illustrated in Figs. 1 land 2 is shown as incorporated in a sewing machine having a bracket-arm terminating in an openended head 16 having a cover or face plate 17. A mainshaft 18 is disposed in suitable bearings provided in the bracket-arm 15. The main-shaft 18 is driven by a means, not shown, and the driving end of the main-shaft 18 carries a counterbalanced crank 19 equipped with a crank pin 21 connected by a link 22 to a collar 23 suitably secured to a needle-bar 24.

The needle-bar 24 carries a conventional needle clamp 25:3 and needle 27, the needle-bar 24 being reciprocably mounted in bearings provided in a vibratory or swinging gate 2S. The gate 28 is pivotally hung to swing about a pivot stud 29 carried by the head 16. Swinging movement of the gate 28 is induced by a conventional pitman 31 positioned -within the bracket-arm 15. One end of the pitman 31 is drilled to Ireceive Ithe end of a headed pin 32, the pitman 31 being secured to the pin 32 by means of a set screw 33.

The pin 32 passes through an unthreaded hole 34 in the gate 28 and the end of the pin 32, remote from where it is secured Ito the pitman 31, pivotally supports the knee of a bell-crank lever 36 having a horizontal arm 37 and a vertical arm 38. The end of the arm 37 is provided with a slotted hole 39 through which passes a clamp screw 41 threaded into the gate 28. The free end of the arm 38 carries a spring-pin 42 which enters the small end of a beehive compression spring 43. The large end of the spring 43 is received by one end of a flanged spring-pin 44 of which the other end enters a hole 46 formed in the head 16 of the sewing machine.

In operation, the screwV 41 is tightened thereby clamping the bell-crank lever 36 to the gate 28. -Because of this the spring 43, which is compressed between the pin 44 andthe arm 38 of the bell-crank lever 36, biases the lower end of the gate 28 `to swing toward the left `as seen in Fig. l. Endwise reciprocation of the pitman 31 causes the gate 28 to swing back and forth about the pivot stud 29. The amount of pressure applied by the spring 43 can be adjusted by loosening the clamp screw 41 and adjusting the arm 37 within limits of the slotted hole 39. Upward adjustment (Fig. l) Iof the arm 37 increases the effect of the spring 43, whereas downward :adjustment of the arm 37 decreases the effect of the spring 43.

Reference to the drawings shows that the adjusting or clamp screw 41 is easily accessible when the face plate 17 is removed and that the screw 41 and lever 36 'are covered and out of sight when the face plate 17 is secured to the head 16.

Having thus described the invention, what I claim heremls:

1. In a zigzag sewing machine having a bracket-arm head, a swinging gate mounted in said head, a needle-bar reciprocably mounted in said gate, a pitman pivotally connected to said gate `and inducing swinging movement thereof; a pivot-pin carried by said gate, a bell-crank lever pivoted on said pivot-pin, said bell-crank lever having two arms, one of said arms being provided with a slotted hole adjacent to the free end thereof and spaced from -said pivot-pin', a clamp-screw passing through said slotted hole and threaded into said gate thereby adjustably securing said bell-crank lever to said gate, and a compression spring compressed between the second arm of said bell-crank lever and said bracket-arm head.

2. In a zigzag sewing machine having a bracket-arm head, a swinging gate mounted in said head, a needle-bar reciprocably mounted in said gate, a pitman pivotally connected to 'said gate `and inducing the swinging movement thereof, a pivot-pin carried by said gate, a bell-crank lever pivoted on said pivot-pin, said bell-crank lever having a vertical arm and a horizontal arm, said horizontal arm being provided with ya slotted hole spaced from said pivot pin and adjacent to the free end of said horizontal arm, a clamp-screw passing through said slotted hole and threaded into said gate thereby adjnstably securing said bell-crank lever to said gate, a first spring engaging means carried by the lfree end of said vertical arm; a second spring engaging means carried by the sewing machine; and a -beehive compression spring compressed between said two spring engaging means.

3. `In a zigzag sewing machine having a bracket-arm head and a face-plate for said head, a swinging gate, a needle-bar reciprocably mounted in said gate, ra pitman pivotally connected to said gate and inducing the swingingv movement thereof, a pivot-pin carried by said gate, a bellcrank lever pivoted on said pivot-pin, said bell-crank lever having a vertical arm and .a horizontal arm, said horizontal arm being provided with a slotted hole spaced from said pivot pin and adjacent to the free end of said horizontal arm, a clamp-screw passing through said slotted hole and threaded into said -gate thereby adjustably securing said bell-crank lever to said gate, said clamp screw being accessible when said face-plate is removed :andgbeing c overed when said face-plate is secured to` said bracket-arm head, Je. rst 'spring engaging means carried by .the freeendof `said vertical arm, a vsecond spring enn gaging means carried by the lsewing machine, and a beehive compression spr-ing compressed between said two spr-ing enga-ging means.. K 4

4. In zigzag.sewingmaehinewhaving a bracket-arm head member, a.` swinging gate member mounted in said head member, a needle-bar reciproctrbly mounted in said gate member, means swinging said `gate member, a pivot mounted 'on one of said members, a lever pivotally 4 mounted on said pivot, means spaced from sid pivotfadjustably securing said lever to the member on which the pivot is mounted, a compression spring, and' means mounting said spring between said lever and the other of said members.

References Cited in the le of this patent UNITED STATES PATENTS 

